Skywatcher Cees Bassa from The Netherlands reported a chance sighting of a bright satellite of unknown identity, observed early on April 11. He estimated a circular orbit of about 54.5 deg inclination and 220 miles (355 kilometers) altitude.

Bassa alerted the satellite observing network and others that this could be OTV-5.

The object seen had been observed last October by another satellite spotter, Russell Eberst in Edinburgh, United Kingdom, who had reported a satellite of similar brightness and similar orbit.

Credit: Boeing/screengrab

Close correlation

“I produced rough search elements, that proved too rough to recover the object,” said Ted Molczan, a Toronto-based satellite analyst. “I found, with very slight tweaks, the preliminary orbit that Cees had posted could be made to fit both his and Russell’s observations,” he told Inside Outer Space.

Bassa noted the close correlation of the orbit with the launch of OTV-5.

Meanwhile, another satellite tracker, Marco Langbroek, also in The Netherlands, made note that the U.S. Air Force had earlier announced that the inclination of OTV-5 would be the highest of the series to-date.

“The fifth OTV mission will also be launched into, and landed from, a higher inclination orbit than prior missions to further expand the X-37B’s orbital envelope,” explained the Air Force in a pre-launch statement.

This orbit also passes very close, within 2 degrees longitude from Cape Canaveral, at the time of the OTV-5 launch. “Looks like a pretty probable identification,” Langbroek reports.

Ground track

“Cees recovered the object, which can now be identified beyond reasonable doubt as OTV-5,” Molczan said. “As Cees cautions, further tracking may reveal a bit more eccentric orbit, but the mean altitude is about 355 kilometers, and the inclination is close to 54.5 degrees.”

“I estimate that the ground track nearly repeats at intervals of about 31 revolutions, or about two days,” Molczan explains. “Similar behavior has been seen during portions of all previous OTV missions. If it carries an imaging payload, then the orbit affords frequent revisit of targets, but it could serve some other operational purpose that I cannot guess.”

The U.S. Air Force’s X-37B Orbital Test Vehicle 4 is seen after landing at NASA ‘s Kennedy Space Center Shuttle Landing Facility in Florida on May 7, 2017.Credit: U.S. Air Force courtesy photo

Rapid space access

When OTV-5 will return to Earth is anybody’s guess. The X-37B program completed its fourth mission on May 7, 2017, landing after 718 days in orbit and extending the program’s total number of days spent in orbit to 2,085.

The current mission is hosting the Air Force Research Laboratory Advanced Structurally Embedded Thermal Spreader payload to test experimental electronics and oscillating heat pipe technologies in the long duration space environment.

“The many firsts on this mission make the upcoming OTV launch a milestone for the program,” said Randy Walden, the director of the Air Force Rapid Capabilities Office. “It is our goal to continue advancing the X-37B OTV so it can more fully support the growing space community,” prior to the space plane’s liftoff.

For more details on this current mission, go to my earlier Space.com story: